[MENFORCER-372] Drop PlexusTestCase and junit:junit dependency

Closes #125
diff --git a/enforcer-rules/pom.xml b/enforcer-rules/pom.xml
index 720b84b..719af6a 100644
--- a/enforcer-rules/pom.xml
+++ b/enforcer-rules/pom.xml
@@ -64,7 +64,7 @@
     </dependency>
     <dependency>
       <groupId>org.apache.maven.shared</groupId>
-      <artifactId>maven-common-artifact-filters</artifactId>
+      <artifactId>maven-shared-utils</artifactId>
     </dependency>
     <dependency>
       <groupId>org.codehaus.plexus</groupId>
@@ -108,11 +108,6 @@
       <scope>test</scope>
     </dependency>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>
       <scope>test</scope>
@@ -127,10 +122,6 @@
         </exclusion>
       </exclusions>
     </dependency>
-    <dependency>
-      <groupId>org.apache.maven.resolver</groupId>
-      <artifactId>maven-resolver-util</artifactId>
-    </dependency>
     <!-- needed for ArtifactCollector and maven-dependency-tree 2.2 -->
     <dependency>
       <groupId>org.apache.maven</groupId>
diff --git a/enforcer-rules/src/test/java/org/apache/maven/plugins/enforcer/MockProject.java b/enforcer-rules/src/test/java/org/apache/maven/plugins/enforcer/MockProject.java
index 42ad593..3851188 100644
--- a/enforcer-rules/src/test/java/org/apache/maven/plugins/enforcer/MockProject.java
+++ b/enforcer-rules/src/test/java/org/apache/maven/plugins/enforcer/MockProject.java
@@ -52,7 +52,6 @@
 import org.apache.maven.model.Scm;
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.artifact.InvalidDependencyVersionException;
-import org.codehaus.plexus.PlexusTestCase;
 import org.codehaus.plexus.util.xml.Xpp3Dom;
 
 /**
@@ -348,7 +347,8 @@
     {
         if ( baseDir == null )
         {
-            baseDir = new File( PlexusTestCase.getBasedir() );
+            final String path = System.getProperty( "basedir" );
+            baseDir = null != path ? new File( path ) : new File( "" );
         }
         return baseDir;
     }
diff --git a/maven-enforcer-extension/pom.xml b/maven-enforcer-extension/pom.xml
index 5ba08aa..7dcf1ba 100644
--- a/maven-enforcer-extension/pom.xml
+++ b/maven-enforcer-extension/pom.xml
@@ -53,11 +53,6 @@
       <artifactId>maven-core</artifactId>
       <scope>provided</scope>
     </dependency>
-    <dependency>
-      <groupId>org.apache.maven.plugin-tools</groupId>
-      <artifactId>maven-plugin-annotations</artifactId>
-      <scope>provided</scope>
-    </dependency>
    <dependency>
       <groupId>org.apache.maven.plugins</groupId>
       <artifactId>maven-enforcer-plugin</artifactId>
diff --git a/maven-enforcer-plugin/pom.xml b/maven-enforcer-plugin/pom.xml
index 5c61f31..8818d62 100644
--- a/maven-enforcer-plugin/pom.xml
+++ b/maven-enforcer-plugin/pom.xml
@@ -41,10 +41,6 @@
   <dependencies>
     <dependency>
       <groupId>org.apache.maven</groupId>
-      <artifactId>maven-artifact</artifactId>
-    </dependency>
-    <dependency>
-      <groupId>org.apache.maven</groupId>
       <artifactId>maven-plugin-api</artifactId>
     </dependency>
     <dependency>
@@ -52,10 +48,6 @@
       <artifactId>maven-core</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.codehaus.plexus</groupId>
-      <artifactId>plexus-utils</artifactId>
-    </dependency>
-    <dependency>
       <groupId>org.apache.maven.enforcer</groupId>
       <artifactId>enforcer-api</artifactId>
     </dependency>
@@ -69,22 +61,12 @@
       <type>test-jar</type>
     </dependency>
     <dependency>
-      <groupId>org.apache.maven.plugin-testing</groupId>
-      <artifactId>maven-plugin-testing-harness</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
       <groupId>org.apache.maven.plugin-tools</groupId>
       <artifactId>maven-plugin-annotations</artifactId>
       <scope>provided</scope>
     </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
-      <artifactId>mockito-core</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.mockito</groupId>
       <artifactId>mockito-junit-jupiter</artifactId>
       <scope>test</scope>
     </dependency>
@@ -93,11 +75,6 @@
       <artifactId>junit-jupiter-api</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
 
   <build>
diff --git a/pom.xml b/pom.xml
index defc8f3..521bcfb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -68,6 +68,7 @@
     <maven.version>3.1.1</maven.version>
     <maven.site.path>enforcer-archives/enforcer-LATEST</maven.site.path>
     <javaVersion>8</javaVersion>
+    <mockito.version>4.0.0</mockito.version>
     <project.build.outputTimestamp>2021-07-26T21:04:56Z</project.build.outputTimestamp>
   </properties>
 
@@ -128,22 +129,15 @@
         <scope>test</scope>
       </dependency>
       <dependency>
-        <!-- Needed as PlexusTestCase extends junit.framework.TestCase -->
-        <groupId>junit</groupId>
-        <artifactId>junit</artifactId>
-        <version>4.13.2</version>
-        <scope>test</scope>
-      </dependency>
-      <dependency>
         <groupId>org.mockito</groupId>
         <artifactId>mockito-core</artifactId>
-        <version>4.0.0</version>
+        <version>${mockito.version}</version>
         <scope>test</scope>
       </dependency>
       <dependency>
         <groupId>org.mockito</groupId>
         <artifactId>mockito-junit-jupiter</artifactId>
-        <version>4.0.0</version>
+        <version>${mockito.version}</version>
         <scope>test</scope>
       </dependency>
       <dependency>
@@ -179,9 +173,9 @@
         <version>3.1.0</version>
       </dependency>
       <dependency>
-        <groupId>org.apache.maven.resolver</groupId>
-        <artifactId>maven-resolver-util</artifactId>
-        <version>1.6.1</version>
+        <groupId>org.apache.maven.shared</groupId>
+        <artifactId>maven-shared-utils</artifactId>
+        <version>3.3.4</version>
       </dependency>
       <dependency>
         <groupId>org.assertj</groupId>
@@ -220,6 +214,11 @@
           <artifactId>maven-jxr-plugin</artifactId>
           <version>3.1.1</version>
         </plugin>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-surefire-plugin</artifactId>
+          <version>3.0.0-M5</version>
+        </plugin>
       </plugins>
     </pluginManagement>
     <plugins>